The present invention relates to a method of producing a copper-clad laminated board for a printed circuit board, which uses a mold releasing film, such as a polyamide-type film.
Methods of producing a copper-clad laminated board (hereinafter abbreviated as "CCLB") for a multi-layered printed circuit board (hereinafter abbreviated as "MLPCB") include press molding of a both-side roughened copper foil (hereinafter abbreviated as "BSRCF") placed on a single prepreg therewith, and press molding of BSRCFs placed on both sides of a lamination of multiple prepregs therewith. The roughening of a copper foil is performed to improve the bonding between the copper foil and the prepreg.
However, a BSRCF has a shortcoming that when it is pressed with a prepreg, the fine ruggedness on the roughened surface of the copper foil, which is pressed with a press plate, is likely to be crushed.
To prevent the crushing of the ruggedness on the surface of the BSRCF, a metal film such as a copper foil or aluminum foil, or a conventionally used organic film such as polypropylene, polyethylene terephthalate, polyethylene, triphenylpentene or TEDRA (trade name of a resin film made by Du Pont) is placed between a press plate and a BSRCF at the time of press molding.
Hereupon, prepregs were acquired by permeating a thermosetting resin, such as phenolic resin, an epoxy resin, a polyimide resin, an epoxy modified polyimide resin or a cyanate ester resin, in a fabric or nonwoven fabric of a glass fiber, an aramid fiber, a polyester fiber, a carbon fiber, or paper, and drying the resultant structure.
However, when a metal foil is used, when there is a resin powder or the like remaining on the press plate, the metal foil stick on the press plate at that remaining portion and remains as foreign matter on the press plate, producing so-called stamping marks. Besides, when the aforementioned plastic film is used, it does not have the desirable property of separation from the press plate. Also, even when the plastic film is peeled off from the BSRCF, printing of that film surface on the surface of the BSRCF would be seen on the electron microscopic level due to cleavage fracture of the film used. This printing will have a bad effect upon the subsequent process of the molded CCLB.